DE1083897B - Pneumatic drive, which can be acted upon on both sides, for electrical switches with venting devices for switching operations in rapid succession - Google Patents

Description

GERMAN

In order to switch between two successive circuits such. B. for short breaks, To achieve very short times, it is already known to design pneumatic drives in such a way that that the cylinder space filled with the drive air already during the switching movement, i.e. still before the start of the following switching process, is vented. The ventilation is done mechanically actuated devices, e.g. B. slides which are coupled to the drive piston by a linkage. Such drives are, however, at very high switching speeds, which are over 20 m / sec can, mechanically stressed and therefore easily fail.

It has already been proposed to design the drive piston in two parts, with an inner, The piston part, which is under spring pressure and is connected to the shift linkage, closes shortly before termination the switch-off movement of the outer part and thereby the drive air over the way exposes the piston opening and a vent opening at the end of the cylinder. The venting of the drive air filled cylinder space is done by the drive piston itself, so that also very short switching times can be achieved without mechanical damage to the drive at very high Switching speeds are to be feared. However, such a vent is only suitable for one-sided pneumatic actuation of the drive piston.

The invention also relates to a pneumatic drive for electrical switches with venting devices for switching operations in rapid succession, which can preferably be acted upon on both sides and in which the venting devices are also controlled so that the cylinder space filled with the drive air is initially closed during the switching movement, but before the start the following switching process is vented. According to the invention, pneumatically actuated venting devices connected to the cylinder wall are provided, which become effective shortly before or at the end of the switching process, regardless of the position of the drive piston. Such a drive has the advantage that the venting can be carried out at any point in time, namely only when the drive piston has already reached its end position. This fact is particularly important in the event that the piston rebounds in the end position as a result of high speed and the tip of the switch pin emerges from the most favorable extinguishing area and causes the arc to re-ignite. If, however, the venting does not take place until the end of the switching movement, pneumatic drive, preferably actuatable on both sides

for electrical switches

with ventilation devices

for quickly successive

Circuits

Applicant:

LICENTIA Patent-Verwaltungs-G.m.b.H., Frankfurt / M., Theodor-Stern-Kai 1

Dr.-Ing. Karl Kxiechbaum, Kassel, has been named as the inventor

2

then the air still present in the drive cylinder prevents the piston from rebounding more strongly. the Pneumatic venting devices are also very simple in construction and can not can be damaged by very high switching speeds.

Valves with pressure compensation have proven to be particularly useful venting devices work between their cylinder chambers separated by a piston, reducing the closing time of the valve is independent of the duration of the compressed air. The pressure equalization can for example be carried out through bores in the piston or through overflow channels in the valve cylinder. While a spring supplying the restoring force must be provided in these valves, can these are omitted if the restoring force is obtained by using the valve piston as a differential piston is trained.

In order to shorten the switching times even further, it is also advisable to remove the ventilation of the drive cylinder from that of the air supply line. This separation · can be carried out at a predetermined pressure difference between the two rooms. It becomes through it practically only the drive cylinder is vented and a countermovement can already be switched on as long as compressed air from the previous

009 547/301

Claims (8)

outgoing switching process is present in the associated supply line. In order to separate the spaces from one another, an element which is under spring pressure and is arranged centrally in the drive cylinder at the feed point for the pressurized gas can preferably be provided; which expediently simultaneously serves as a guide for the switch pin and closes the cylinder chamber when the pressure in the supply line drops. '"". For a more detailed explanation of the invention, exemplary embodiments are shown in the drawing. Fig. 1 illustrates one. Section through a drive cylinder with only one pneumatically actuated vent valve, FIG. 2 shows a section through a drive cylinder with two vent valves. The drive cylinder 1 has a drive piston 2 with a switching pin 3. The compressed air is fed to the drive via the inlet opening 4 for the switch-off movement and via the inlet opening 5 for the switch-on movement. The compressed air for the switch-off movement leads through a centrally located valve 6, which is in the; Rest state is held in the closed position by a spring 7 with an adjustable bias. This valve is designed so that it also serves as a switch pin guide. At the end of the cylinder there is a ventilation opening 8 which can be closed by a valve 9. That. Valve 9 has a piston 10 under spring pressure and a slide H. The valve piston 10 is provided with small bores 12. The drive shown works in the following way: When the switch-off compressed air is supplied, the valve 6 opens first. The compressed air penetrates into the drive cylinder 1 and moves the piston 2 with the switching pin 3 into the switch-off position. As soon as the piston 2 overflows the opening 8, the drive air that has flown into the cylinder escapes to the outside, so that this space is already vented for subsequent activation. When the switch-on is switched on, compressed air passes through the inlet opening 5 behind the drive piston 2 and at the same time also onto the piston 12 of the valve 9. This valve is closed immediately so that the switch-on air cannot escape from the vent opening 8. The piston 2 moves into the on position. In the meantime, air has penetrated through the bores 12 behind the piston 10, so that a pressure equalization between the two cylinder chambers is achieved. As a result of the spring action, the valve 9 opens again, regardless of the duration of the pending compressed air, so that the cylinder chamber is now immediately vented and an immediately following switching movement is made possible. The drive piston itself is expediently designed to be resilient in order to reduce the impact stress that occurs. The drive according to FIG. 1 can also be changed in such a way that two valves are arranged on the cylinder, one of which is actuated by the switch-on air and the other by the switch-off air, as FIG. 2 shows. A second vent valve may be required if the drive piston does not spring back too far. In FIG. 2, 1 again denotes the drive cylinder with the drive piston 2 and the switching pin 3; 6 is the centrally arranged inlet valve for the switch-off air. On the cylinder are a vent valve 13 for the switch-on air and a. Vent valve 14 attached for the switch-off air. Each of these valves contains a piston 15 or 16, which, when exposed to compressed air from the outside, rests against an edge and thereby seals off the venting channel 17. When switched on, compressed air is supplied through the inlet opening 18. The piston 2 moves in the direction of the switch-on position. At the same time the vent valve 13 is closed. The vent valve 14, on the other hand, is opened immediately after the vent channel 17 has overflowed by the switch-on air located in the cylinder. Since the piston 15 of the valve 13 is designed as a differential piston, the compressed air from the cylinder also causes the valve 13 to open, so that the cylinder space is vented. The initiated switching movement is not impaired by this venting, since enough kinetic energy is stored in the drive piston and there is also a residual pressure within the cylinder space. When it is switched off, compressed air flows through: the central valve 6 into the cylinder space and at the same time through the opening 19 into the valve 14, so that it is closed. After overflowing the channel 17, compressed air also reaches the other side of the piston 16. This piston does not need to be designed as a differential piston, since a longer pause time can be permitted with an off-on switch. The valve 14 is therefore opened after the compressed air has been switched off by the compressed air present in the cylinder, so that, since the valve 13 is still open from the switch-on process, this side of the drive is also vented. ". Patent claims: 1. Pneumatic drive, preferably acted upon on both sides, for electrical switches with venting devices for circuits in rapid succession, e.g. B. for short interruptions in which the ventilation devices are controlled so that the cylinder space filled with the drive air is initially closed during the switching movement, but is already vented before the beginning of the following switching process, characterized in that pneumatically operated ventilation devices connected to the cylinder wall are provided, which are effective regardless of the position of the drive piston shortly before or at the end of the switching process. 2. Drive according to claim 1, characterized in that vent valves with a Working pressure equalization between the cylinder chambers separated by a piston is provided are. 3. Drive according to claim 2, characterized in that for carrying out the pressure equalization bores are provided in the piston. 4. Drive according to claim 2, characterized in that for carrying out the pressure equalization the valve cylinder has overflow channels. 5. Drive according to claim 2, characterized in that to obtain a restoring force the valve piston is designed as a differential piston. 6. Drive according to claim 1, characterized in that the first with the drive air connected cylinder space from the supply lines for the drive air at an adjustable _ pressure difference between these two rooms will. 7. Drive according to claim 6, characterized in that a spring pressure in the drive cylinder standing, centrally arranged element (6) is provided, which is useful at the same time as Guide for the switch pin is used. 8. Drive according to claim 1, characterized in that to avoid shock loading
forms is. the drive piston is resilient Publications considered: German Patent No. 751 183. Older patents considered: German Patent No. 1 015 517. 1 sheet of drawings © 009 547/301 6.60